Risk assessment of rainstorm disaster based on scenario construction

China, a country prone to frequent rainstorms, faces the pervasive threat of rainstorm disasters in most of its regions. This study aims to enhance the scientific understanding of the risks and impacts associated with rainstorm disasters. The focus of the research is on scenario construction, incorporating the consideration of disaster chains and utilizing various technologies to conduct a comprehensive assessment of rainstorm disaster risks. The "Scenario-Task-Capability" methodology is employed to analyze the characteristics of these disaster scenarios. In the "capability" analysis, a disaster chain is established, and an evolution network model for extremely heavy rainstorm disaster events is formulated. Taking into account the nature of risk sources, regional risk tolerance capacity, and risk control abilities, among other factors, a time series-based rainstorm disaster risk assessment model is developed. This model is validated using a case study in the southwest of China. The findings reveal that the comprehensive risks of rainstorm disasters in the study area are predominantly of medium and high levels, constituting 27.968% and 28.101% of the total area, respectively. These risks are concentrated in the central-west and northeast regions of the study area. Low-risk areas cover 21.381% of the total area, primarily located in the central part of the study area and dispersed in a southwest direction. An extremely high-risk area, encompassing 22.549% of the total area, is concentrated in the central and scattered northern regions. This study constructs a time-series risk assessment model for the rainstorm disaster chain with universal adaptability, which enriches the relevant theories of the rainstorm disaster chain evolution network; and it can also study the evolution of the direct risk and comprehensive risk of each disaster event node over time, providing a more systematic and complete assessment of the rainstorm disaster chain, as well as an analytical model and quantitative decision-making basis for different regions to assess comprehensive risks of rainstorm disasters and enhance disaster prevention and mitigation capabilities.